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/*
* RTP packetizer for HEVC/H.265 payload format (draft version 6)
* Copyright (c) 2014 Thomas Volkert <thomas@homer-conferencing.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avformat.h"
#include "avc.h"
#include "rtpenc.h"
#define RTP_HEVC_HEADERS_SIZE 3
static const uint8_t *avc_mp4_find_startcode(const uint8_t *start, const uint8_t *end, int nal_length_size)
{
unsigned int res = 0;
/* is the given data big enough for 1 NAL unit? */
if (end - start < nal_length_size)
return NULL;
while (nal_length_size--)
res = (res << 8) | *start++;
if (res > end - start)
return NULL;
return start + res;
}
static void nal_send(AVFormatContext *ctx, const uint8_t *buf, int len, int last_packet_of_frame)
{
RTPMuxContext *rtp_ctx = ctx->priv_data;
int rtp_payload_size = rtp_ctx->max_payload_size - RTP_HEVC_HEADERS_SIZE;
int nal_type = (buf[0] >> 1) & 0x3F;
/* send it as one single NAL unit? */
if (len <= rtp_ctx->max_payload_size) {
/* use the original NAL unit buffer and transmit it as RTP payload */
ff_rtp_send_data(ctx, buf, len, last_packet_of_frame);
} else {
/*
create the HEVC payload header and transmit the buffer as fragmentation units (FU)
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|F| Type | LayerId | TID |
+-------------+-----------------+
F = 0
Type = 49 (fragmentation unit (FU))
LayerId = 0
TID = 1
*/
rtp_ctx->buf[0] = 49 << 1;
rtp_ctx->buf[1] = 1;
/*
create the FU header
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|S|E| FuType |
+---------------+
S = variable
E = variable
FuType = NAL unit type
*/
rtp_ctx->buf[2] = nal_type;
/* set the S bit: mark as start fragment */
rtp_ctx->buf[2] |= 1 << 7;
/* pass the original NAL header */
buf += 2;
len -= 2;
while (len + RTP_HEVC_HEADERS_SIZE > rtp_ctx->max_payload_size) {
/* complete and send current RTP packet */
memcpy(&rtp_ctx->buf[RTP_HEVC_HEADERS_SIZE], buf, rtp_payload_size);
ff_rtp_send_data(ctx, rtp_ctx->buf, rtp_ctx->max_payload_size, 0);
buf += rtp_payload_size;
len -= rtp_payload_size;
/* reset the S bit */
rtp_ctx->buf[2] &= ~(1 << 7);
}
/* set the E bit: mark as last fragment */
rtp_ctx->buf[2] |= 1 << 6;
/* complete and send last RTP packet */
memcpy(&rtp_ctx->buf[RTP_HEVC_HEADERS_SIZE], buf, len);
ff_rtp_send_data(ctx, rtp_ctx->buf, len + 2, last_packet_of_frame);
}
}
void ff_rtp_send_hevc(AVFormatContext *ctx, const uint8_t *frame_buf, int frame_size)
{
const uint8_t *next_NAL_unit;
const uint8_t *buf_ptr, *buf_end = frame_buf + frame_size;
RTPMuxContext *rtp_ctx = ctx->priv_data;
/* use the default 90 KHz time stamp */
rtp_ctx->timestamp = rtp_ctx->cur_timestamp;
if (rtp_ctx->nal_length_size)
buf_ptr = avc_mp4_find_startcode(frame_buf, buf_end, rtp_ctx->nal_length_size) ? frame_buf : buf_end;
else
buf_ptr = ff_avc_find_startcode(frame_buf, buf_end);
/* find all NAL units and send them as separate packets */
while (buf_ptr < buf_end) {
if (rtp_ctx->nal_length_size) {
next_NAL_unit = avc_mp4_find_startcode(buf_ptr, buf_end, rtp_ctx->nal_length_size);
if (!next_NAL_unit)
next_NAL_unit = buf_end;
buf_ptr += rtp_ctx->nal_length_size;
} else {
while (!*(buf_ptr++)) ;
next_NAL_unit = ff_avc_find_startcode(buf_ptr, buf_end);
}
/* send the next NAL unit */
nal_send(ctx, buf_ptr, next_NAL_unit - buf_ptr, next_NAL_unit == buf_end);
/* jump to the next NAL unit */
buf_ptr = next_NAL_unit;
}
}
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